Couple of things:
- you “looked” at the block and head, it’s unlikely that just by looking at them, you’d be able to see the problem. Just my experience, unless it’s something catastrophic.
- how much is your time worth swapping parts around? I would think the better option would be 1-buy the tool(s) to diagose your problem properly or 2-bring it to someone who has the tools to diagnose your problem properly
- if you choose option 1, then get yourself a leakdown tester
- the only way you can be absolutely sure you don’t have air pockets or to put a vacuum on the cooling system before filling it.
I use this, but I’m sure there are other more resonably-priced alternatives
